bnxt_en: Fix ethtool -l pre-set max combined channel.

With commit d1e7925e ("bnxt_en: Centralize logic to reserve rings."),
ring allocation for combined rings has become stricter.  A combined
ring must now have an rx-tx ring pair.  The pre-set max. for combined
rings should now be min(rx, tx).

Fixes: d1e7925e ("bnxt_en: Centralize logic to reserve rings.")
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c

@@ -357,7 +357,7 @@ static void bnxt_get_channels(struct net_device *dev,
 	int max_rx_rings, max_tx_rings, tcs;
 
 	bnxt_get_max_rings(bp, &max_rx_rings, &max_tx_rings, true);
-	channel->max_combined = max_t(int, max_rx_rings, max_tx_rings);
+	channel->max_combined = min_t(int, max_rx_rings, max_tx_rings);
 
 	if (bnxt_get_max_rings(bp, &max_rx_rings, &max_tx_rings, false)) {
 		max_rx_rings = 0;